chore: Optimize NetworkBehaviour.NetworkManager property#3700

EmandM wants to merge 2 commits intodevelop-2.0.0Unity-Technologies/com.unity.netcode.gameobjects:develop-2.0.0from

chore/optimize-networkbehaviour-networkmanager-propertyUnity-Technologies/com.unity.netcode.gameobjects:chore/optimize-networkbehaviour-networkmanager-propertyCopy head branch name to clipboard